In Plato’s philosophy, the highest ideal and metaphysical entity is a concept known as “The Good”. The Good is described as analogous to the sun, in that it is said to make the objects of reason intelligible much as the sun’s rays make physical objects visible. The Good is the greatest of Plato’s Forms, which are archetypal concepts which can only be approximated by physical objects and entities. The most noble ideals, such as Truth, Justice, Logic or Honour are merely aspects or derivations of The Good.

Close examination of Plato’s description of The Good reveals useful commonalities with similarly unifying concepts from Eastern philosophy, such as the Tao and Brahman. To varying ways and degrees, these concepts share the common feature of being indefinable. Any attempt to define a highest principle will inevitably only capture part of the idea, and thereby be an inherently false definition. Mathematicians might think of the ideal (principle, function, curve) as a kind of singularity which definitions can only approach asymptotically, as approximations. In practical terms, this means that we can (and should) strive toward the ideal of a Good which transcends all other principles, but that we can never actually reach it.